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1.
Can Pharm J (Ott) ; 153(2): 101-107, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32206155

RESUMO

BACKGROUND: Helicobacter pylori is identified by the World Health Organization as a major risk factor of gastritis, peptic ulcer disease and gastric carcinomas. As point-of-care screening technology becomes more widely available, pharmacists are ideally suited to use this tool to screen patients with H. pylori infection. PURPOSE: The objective of this study was to evaluate the feasibility of implementing point-of-care screening technology for H. pylori into community pharmacy practice and to assess the number of patients who are positively identified as a result of testing. METHODS: Three pharmacies in Toronto, Ontario, offered H. pylori screening as part of their clinical programs. Pharmacists enrolled patients with symptoms of dyspepsia and/or receiving acid suppressant therapy for >6 weeks. Decision to screen was based on the Canadian Helicobacter Study Group Consensus (CHSG). Patients were screened using the Rapid Response H. pylori test. RESULTS: Seventy-one patients were recruited, with a mean age of 46.3 years. Patients were ethnically diverse, with a significant proportion (59.2%) identified as being born outside of North America, including Asia (26.8%), Africa (9.9%), the Middle East (7%), Europe (9.9%) and South and Central America (5.6%). Overall, the detection rate of H. pylori infection was 21%. North Americans had the lowest incidence of an undiagnosed H. pylori infection (6.9%). Europeans (28.6%), Middle Easterners (20%) and Asians (21.1%) had a moderate incidence, followed by the highest prevalence in those of African descent (71.4%). CONCLUSION: These results highlight the readiness of community pharmacists to adopt H. pylori screening into practice and to leverage this novel technology to positively identify and treat undiagnosed H. pylori infection. Can Pharm J (Ott) 2020;153:xx-xx.

2.
J Acquir Immune Defic Syndr ; 95(4): 362-369, 2024 04 01.
Artigo em Inglês | MEDLINE | ID: mdl-38412047

RESUMO

BACKGROUND: Preexposure prophylaxis (PrEP) use remains limited and inequitable, and strategies are needed to improve PrEP provision in primary care. METHODS: We conducted a cluster randomized trial at Kaiser Permanente, San Francisco, to evaluate the effectiveness of a clinical decision support intervention guided by an electronic health record (EHR)-based HIV risk prediction model to improve PrEP provision. Primary care providers (PCPs) were randomized to usual care or intervention, with PCPs who provide care to people with HIV balanced between arms. PCPs in the intervention arm received an EHR-based staff message with prompts to discuss HIV prevention and PrEP before upcoming in-person or video visits with patients whose predicted 3-year HIV risk was above a prespecified threshold. The main study outcome was initiation of PrEP care within 90 days, defined as PrEP discussions, referrals, or prescription fills. RESULTS: One hundred twenty-one PCPs had 5051 appointments with eligible patients (2580 usual care; 2471 intervention). There was a nonsignificant increase in initiation of PrEP care in the intervention arm (6.0% vs 4.5%, HR 1.32, 95% CI: 0.84 to 2.1). There was a significant interaction by HIV provider status, with an intervention HR of 2.59 (95% CI: 1.30 to 5.16) for HIV providers and 0.89 (95% CI: 0.59 to 1.35) for non-HIV providers (P-interaction <0.001). CONCLUSION: An EHR-based intervention guided by an HIV risk prediction model substantially increased initiation of PrEP care among patients of PCPs who also care for people with HIV. Higher-intensity interventions may be needed to improve PrEP provision among PCPs less familiar with PrEP and HIV care.


Assuntos
Fármacos Anti-HIV , Infecções por HIV , Profilaxia Pré-Exposição , Humanos , Infecções por HIV/tratamento farmacológico , Infecções por HIV/prevenção & controle , Registros Eletrônicos de Saúde , Cognição , Prescrições , Fármacos Anti-HIV/uso terapêutico
3.
Can J Kidney Health Dis ; 7: 2054358120922617, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32523707

RESUMO

BACKGROUND: Chronic kidney disease (CKD) is a condition presenting with long-term slow progression of structural and/or functional damage to the kidneys. Early detection is key to preventing complications and improving outcomes. Point-of-care estimated glomerular filtration rate (eGFR) screening technology allows for detection of abnormal kidney function in the community pharmacy setting. OBJECTIVE: To evaluate the effectiveness of a community pharmacist-directed point-of-care screening program and to identify the prevalence of CKD in high-risk patients. DESIGN: Quantitative observational. SETTING: Four community pharmacies in British Columbia over a 6-month period. PATIENTS: In all, 642 participants with at least one CKD risk factor were identified and screened. Mean age was 60 years and females accounted for 55% of the study population. MEASUREMENTS: Serum creatinine was measured from peripheral blood using the HeathTab® screening system (Piccolo® Renal Function Panel with the Piccolo® blood chemistry analyzer). eGFR was calculated according to the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) formula. METHODS: Patients provided a sample of peripheral blood via a self-administered finger-prick and analytical data to assess kidney function was reported including blood urea nitrogen (BUN), serum creatinine, and electrolytes by the HealthTab® screening system. Once results were available, the pharmacist conducted a comprehensive medication review with the patient and recommended certain follow-up actions if appropriate. RESULTS: CKD risk factor included diabetes (30%), hypertension (45%), cardiovascular disease (12%), family history of kidney disease (13%), age over 55 years (68%), and an Aboriginal, Asian, South Asian, or African ethnic background (82%). A total of 11.5% of patients had eGFR values lower than 60 mL/min (abnormal renal function) and 34% had an eGFR between 60 and 89 mL/min (minimally reduced renal function). Overall pharmacists' actions included blood pressure check (98%), education on CKD and risk factors (89%), medication review (72%), and physician follow-up (38%). Limitations included lack of follow-up beyond the 3-month study period prevented medical confirmation of CKD and limited the ability to quantify the impact of pharmacist interventions on the clinical outcomes of patients with low eGFR. CONCLUSION: These results illustrate the prevalence of abnormal renal function among undiagnosed, high-risk patients in the community. Pharmacists, as the most accessible healthcare practitioners, are ideally positioned to utilize novel point-of care technologies to improve access to CKD screening, facilitate follow-up, and increase awareness around the importance of early detection.


CONTEXTE: L'insuffisance rénale chronique (IRC) est caractérisée par la progression lente et à long terme de lésions rénales structurelles et/ou fonctionnelles. Son dépistage précoce est essentiel pour prévenir les complications et améliorer l'issue des patients. La détection d'une fonction rénale anormale en pharmacie d'officine est rendue possible grâce aux technologies de mesure du DFGe hors laboratoire. OBJECTIF: Évaluer l'efficacité d'un program de dépistage de l'IRC dirigé par les pharmaciens d'officine et établir la prévalence de l'IRC chez les patients présentant un risque élevé. TYPE D'ÉTUDE: Étude quantitative observationnelle. CADRE: L'étude s'est tenue dans quatre pharmacies d'officine de Colombie-Britannique sur une période de six mois. SUJETS: Un total de 642 individus présentant au moins un facteur de risque d'IRC ont fait l'objet d'un dépistage. L'âge moyen se situait à 60 ans et 55 % étaient des femmes. MESURES: La créatinine sérique a été mesurée à partir d'un prélèvement de sang périphérique à l'aide d'un système de criblage HealthTabMD (bilan de la fonction rénale avec l'outil d'analyze chimique du sang PiccoloMD). Le DFG a été estimé à l'aide de l'équation CKD-EPI. MÉTHODOLOGIE: Les patients ont fourni un échantillon de sang périphérique autoprélevé par piqûre au doigt. Les données analytiques pour l'évaluation de la fonction rénale, soit les taux d'azote uréique sanguin (BUN), de créatinine sérique et d'électrolytes, ont été obtenues à l'aide du système de criblage HealthTabMD. Après l'obtention des résultats, le pharmacien a procédé à une revue de la médication avec le patient et recommandé des mesures de suivi lorsque nécessaire. RÉSULTATS: Le diabète (30 %), l'hypertension (45 %), les maladies cardiovasculaires (12 %), le fait d'avoir des antécédents familiaux de néphropathie (13 %), d'être âgé d'au moins 55 ans (68 %) ou d'être d'origine autochtone, asiatique, sud-asiatique ou africaine (82 %) constituaient les facteurs de risque. Des 642 participants, 11,5 % présentaient une fonction rénale anormale (DFGe inférieur à 60 ml/min) et 34 % présentaient une fonction rénale réduite (DFGe entre 60 et 89 ml/min). Les interventions des pharmaciens incluaient la mesure de la pression artérielle (98 %), l'éducation sur l'IRC et ses facteurs de risque (89 %), la revue des médicaments (72 %) et le suivi médical (38 %). LIMITES: L'absence de suivi au-delà des trois mois de l'étude n'a pas permis de confirmer l'IRC ni de mesurer la portée des interventions des pharmaciens sur les résultats cliniques des patients présentant un faible DFGe. CONCLUSION: Ces résultats illustrent la prévalence d'une fonction rénale anormale dans la communauté chez les patients non diagnostiqués présentant un risque élevé. Les pharmaciens, en tant que professionnels de la santé les plus accessibles, sont les mieux placés pour utiliser les technologies d'intervention au point de service et ainsi améliorer l'accès au dépistage de l'IRC, faciliter le suivi et sensibiliser la communauté à l'importance du dépistage précoce de la maladie.

4.
J Res Natl Inst Stand Technol ; 111(4): 257-312, 2006.
Artigo em Inglês | MEDLINE | ID: mdl-27274934

RESUMO

The peak particle size and expanded uncertainties (95 % confidence interval) for two new particle calibration standards are measured as 101.8 nm ± 1.1 nm and 60.39 nm ± 0.63 nm. The particle samples are polystyrene spheres suspended in filtered, deionized water at a mass fraction of about 0.5 %. The size distribution measurements of aerosolized particles are made using a differential mobility analyzer (DMA) system calibrated using SRM(®) 1963 (100.7 nm polystyrene spheres). An electrospray aerosol generator was used for generating the 60 nm aerosol to almost eliminate the generation of multiply charged dimers and trimers and to minimize the effect of non-volatile contaminants increasing the particle size. The testing for the homogeneity of the samples and for the presence of multimers using dynamic light scattering is described. The use of the transfer function integral in the calibration of the DMA is shown to reduce the uncertainty in the measurement of the peak particle size compared to the approach based on the peak in the concentration vs. voltage distribution. A modified aerosol/sheath inlet, recirculating sheath flow, a high ratio of sheath flow to the aerosol flow, and accurate pressure, temperature, and voltage measurements have increased the resolution and accuracy of the measurements. A significant consideration in the uncertainty analysis was the correlation between the slip correction of the calibration particle and the measured particle. Including the correlation reduced the expanded uncertainty from approximately 1.8 % of the particle size to about 1.0 %. The effect of non-volatile contaminants in the polystyrene suspensions on the peak particle size and the uncertainty in the size is determined. The full size distributions for both the 60 nm and 100 nm spheres are tabulated and selected mean sizes including the number mean diameter and the dynamic light scattering mean diameter are computed. The use of these particles for calibrating DMAs and for making deposition standards to be used with surface scanning inspection systems is discussed.

5.
Brain Res Mol Brain Res ; 134(2): 338-44, 2005 Apr 04.
Artigo em Inglês | MEDLINE | ID: mdl-15836929

RESUMO

Cyclin-dependent kinase 5 (cdk5) inhibits neurofilament (NF) anterograde axonal transport while p42/44 mitogen-activated protein kinase (MAPk) promotes it. Since cdk5 is known to inhibit MAP kinase activity, we examined whether or not cdk5 inhibits anterograde NF transport via inhibition of MAPk activity. To accomplish this, we manipulated the activity of these kinases in differentiated NB2a/d1 cells, and monitored anterograde axonal transport of green fluorescent protein-conjugated-NF-M (GFP-M) and cyan fluorescent protein-conjugated (CFP)-tau. The cdk5 inhibitor roscovitine increased anterograde axonal transport of GFP-M and CFP-tau; transfection with cdk5/p25 inhibited transport of both. Inhibition of MAPk activity by PD98059 or expression of dominant-negative MAPk inhibited anterograde GFP-M transport, while expression of constitutively active MAPk enhanced it; these treatments did not affect CFP-tau transport. PD98059 prevented roscovitine-mediated enhancement of GFP-M transport, but did not prevent enhancement of CFP-tau transport. Co-transfection with constitutively activated MAPk prevented the inhibition of GFP-M transport that normally accompanied transfection with cdk5/p25, but did not prevent inhibition of tau transport by cdk5/p25. Finally, the extent of inhibition of GFP-M axonal transport by PD98059 was not additive to that derived from transfection with cdk5/p35, and the increase in NF transport that accompanies roscovitine treatment was not additive to that derived from transfection with constitutively activated MAPk, suggesting that the influence of these kinases on NF transport was within the same, rather than distinct, pathways. These findings suggest that axonal transport of tau and NFs is under the control of distinct kinase cascades, and that cdk5 inhibits NF transport at least in part by inhibiting MAPk.


Assuntos
Transporte Axonal/efeitos dos fármacos , Quinases Ciclina-Dependentes/farmacologia , Proteínas Quinases Ativadas por Mitógeno/farmacologia , Proteínas de Neurofilamentos/metabolismo , Proteínas tau/metabolismo , Animais , Linhagem Celular Tumoral , Quinase 5 Dependente de Ciclina , Interações Medicamentosas , Inibidores Enzimáticos/farmacologia , Flavonoides/farmacologia , Proteínas de Fluorescência Verde/metabolismo , Camundongos , Neuroblastoma , Purinas/farmacologia , Roscovitina , Transfecção/métodos
6.
Burns ; 41(5): 1017-27, 2015 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-25681021

RESUMO

An experimental apparatus designed to study firefighter safety equipment exposed to a thermal environment was developed. The apparatus consisted of an elevated temperature flow loop with the ability to heat the air stream up to 200°C. The thermal and flow conditions at the test section were characterized using thermocouples and bi-directional probes. The safety equipment examined in this study was a self-contained breathing apparatus (SCBA), including a facepiece and an air cylinder. The SCBA facepiece was placed on a mannequin headform and coupled to a breathing simulator that was programmed with a prescribed breathing pattern. The entire SCBA assembly was placed in the test section of the flow loop for these thermal exposure experiments. Three air stream temperatures, 100°C, 150°C, and 200°C, were used with the average air speed at the test section set at 1.4m/s and thermal exposure durations up to 1200 s. Measurements were made using type-K bare-bead thermocouples located in the mannequin's mouth and on the outer surface of the SCBA cylinder. The experimental results indicated that increasing the thermal exposure severity and duration increased the breathing air temperatures supplied by the SCBA. Temperatures of breathing air from the SCBA cylinder in excess of 60°C were observed over the course of the thermal exposure conditions used in most of the experiments. A mathematical model for transient heat transfer was developed to complement the thermal exposure experimental study. The model took into consideration forced convective heat transfer, quasi-steady heat conduction through the composite layers of the SCBA cylinder wall, the breathing pattern and action of the breathing simulator, and predicted air temperatures from the thermally exposed SCBA cylinder and temperatures at the outer surface of the SCBA cylinder. Model predictions agreed reasonably well with the experimental measurements.


Assuntos
Queimaduras por Inalação , Ar Comprimido , Bombeiros , Temperatura Alta/efeitos adversos , Equipamentos e Provisões , Humanos , Modelos Teóricos
7.
J Alzheimers Dis ; 28(3): 497-501, 2012.
Artigo em Inglês | MEDLINE | ID: mdl-22045493

RESUMO

Alzheimer's disease encompasses multiple risk factors; convergence may be necessary for clinical manifestation. Mice received a complete diet or one lacking folate and vitamin E and containing iron as a pro-oxidant, in a standard environment (SE) or a large cage containing objects to stimulate exploration/activity (enriched environment; EE). Mice declined in maze navigation on the deficient versus complete diet in the SE but not the EE. Mice on the complete diet demonstrated superior performance in the EE versus SE. The EE reduced brain lipid and protein oxidation. These findings suggest that maintaining nutrition and activity may delay age-related cognitive decline.


Assuntos
Transtornos Cognitivos/etiologia , Transtornos Cognitivos/prevenção & controle , Suplementos Nutricionais , Meio Ambiente , Deficiência de Ácido Fólico/complicações , Deficiência de Vitamina E/complicações , Animais , Encéfalo/metabolismo , Transtornos Cognitivos/patologia , Modelos Animais de Doenças , Feminino , Masculino , Aprendizagem em Labirinto/fisiologia , Camundongos , Camundongos Endogâmicos C57BL , Estresse Oxidativo/fisiologia , Carbonilação Proteica , Substâncias Reativas com Ácido Tiobarbitúrico/metabolismo
8.
J Virol ; 81(5): 2283-96, 2007 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-17166902

RESUMO

The function of the alphaherpesvirus UL47 tegument protein has not yet been defined. Nonetheless, previous studies with transfected cells have shown that both the herpes simplex virus type 1 homologue (hUL47, or VP13/14) and the bovine herpesvirus type 1 (BHV-1) homologue (bUL47, or VP8) have the capacity to shuttle between the nucleus and the cytoplasm. Furthermore, hUL47 packaged into the virion has also been shown to bind several individual virus-specific RNA transcripts. Here, we extend these observations and show that hUL47 binds a wide range of RNA species in vitro. It has a high affinity for polyadenylated transcripts but has no apparent selectivity for virus-encoded RNA over cellular RNA. We also show that the virion population of bUL47 binds RNA in vitro. However, while purified recombinant hUL47 retains its RNA binding activity, recombinant bUL47 does not, suggesting that the BHV-1 homologue may require virus-induced modification for its activity. We identify the minimal RNA binding domain in hUL47 as a 26-residue N-terminal peptide containing an arginine-rich motif that is essential but not sufficient for optimal RNA binding, and we demonstrate that this RNA binding domain incorporates the hUL47 minimal nuclear localization signal. In addition, we show that soon after hUL47 is expressed during infection, it colocalizes in the infected cell nucleus with ICP4, the major virus transcriptional activator. Using RNA immunoprecipitations, we demonstrate that hUL47 is also bound in vivo to at least one viral transcript, the ICP0 mRNA. Taken together, these results suggest that hUL47 may play a role in RNA biogenesis in the infected cell.


Assuntos
Herpesvirus Humano 1/metabolismo , RNA Viral/metabolismo , Proteínas Virais de Fusão/metabolismo , Sequência de Aminoácidos , Animais , Células COS , Bovinos , Linhagem Celular , Chlorocebus aethiops , Cricetinae , Herpesvirus Bovino 1/genética , Herpesvirus Bovino 1/metabolismo , Herpesvirus Humano 1/genética , Humanos , Técnicas In Vitro , Dados de Sequência Molecular , Sinais de Localização Nuclear/genética , Sinais de Localização Nuclear/metabolismo , Ligação Proteica , Estrutura Terciária de Proteína , RNA/genética , RNA/metabolismo , RNA Viral/genética , Proteínas Recombinantes de Fusão/química , Proteínas Recombinantes de Fusão/genética , Proteínas Recombinantes de Fusão/metabolismo , Transfecção , Células Vero , Proteínas Virais de Fusão/química , Proteínas Virais de Fusão/genética
9.
J Virol ; 80(20): 10021-35, 2006 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-17005680

RESUMO

A new group of nucleocytoplasmic shuttling proteins has recently been identified in the structural proteins encoded by several alphaherpesvirus UL47 genes. Nuclear import and export signals for the bovine herpesvirus type 1 UL47 protein (VP8 or bUL47) have been described previously. Here, we study the trafficking of bUL47 in detail and identify an import signal different from that shown before. It comprises a 20-residue N-terminal peptide that is fully transferable and targets a large, normally cytosolic protein to the nucleus. A conserved RRPRRS motif within this peptide was shown to be essential but not sufficient for nuclear targeting. Using interspecies heterokaryon assays, we further demonstrate that the export activity of the published leucine-rich nuclear export signal (NES) is also transferable to a large protein but is functionally weak compared to the activity of the HIV-1 Rev NES. We show that nuclear export dictated by this bUL47 NES is sensitive to leptomycin B (LMB) and therefore dependent on the export receptor CRM-1. However, nuclear export of full-length bUL47 is fully resistant to LMB, suggesting the presence of an additional NES. We go on to identify a second NES in bUL47 within a 28-residue peptide that is in close proximity to but entirely separable from the N-terminal import signal, and we use fluorescence loss in photobleaching to confirm its activity. This NES is resistant to leptomycin B, and therefore utilizes an export receptor other than CRM-1. As this new sequence bears little similarity to other export signals so far defined, we suggest it may be involved in bUL47 export from the nucleus via a novel cellular receptor.


Assuntos
Núcleo Celular/metabolismo , Citoplasma/metabolismo , Herpesvirus Bovino 1/metabolismo , Sinais de Exportação Nuclear/fisiologia , Proteínas Virais/metabolismo , Motivos de Aminoácidos , Sequência de Aminoácidos , Animais , Inibidores Enzimáticos/farmacologia , Ácidos Graxos Insaturados/farmacologia , Humanos , Carioferinas/antagonistas & inibidores , Camundongos , Microscopia de Fluorescência , Dados de Sequência Molecular , Células NIH 3T3 , Sinais de Exportação Nuclear/efeitos dos fármacos , Sinais de Exportação Nuclear/genética , Receptores Citoplasmáticos e Nucleares/antagonistas & inibidores , Proteínas Recombinantes de Fusão/metabolismo , Proteínas Virais/química , Proteínas Virais/genética , Proteína Exportina 1
10.
J Gen Virol ; 82(Pt 5): 1013-1025, 2001 May.
Artigo em Inglês | MEDLINE | ID: mdl-11297676

RESUMO

The 2A region of the aphthovirus foot-and-mouth disease virus (FMDV) polyprotein is only 18 aa long. A 'primary' intramolecular polyprotein processing event mediated by 2A occurs at its own C terminus. FMDV 2A activity was studied in artificial polyproteins in which sequences encoding reporter proteins flanked the 2A sequence such that a single, long, open reading frame was created. The self-processing properties of these artificial polyproteins were investigated and the co-translational 'cleavage' products quantified. The processing products from our artificial polyprotein systems showed a molar excess of 'cleavage' product N-terminal of 2A over the product C-terminal of 2A. A series of experiments was performed to characterize our in vitro translation systems. These experiments eliminated the translational or transcriptional properties of the in vitro systems as an explanation for this imbalance. In addition, the processing products derived from a control construct encoding the P1P2 region of the human rhinovirus polyprotein, known to be proteolytically processed, were quantified and found to be equimolar. Translation of a construct encoding green fluorescent protein (GFP), FMDV 2A and beta-glucuronidase, also in a single open reading frame, in the presence of puromycin, showed this antibiotic to be preferentially incorporated into the [GFP2A] translation product. We conclude that the discrete translation products from our artificial polyproteins are not produced by proteolysis. We propose that the FMDV 2A sequence, rather than representing a proteolytic element, modifies the activity of the ribosome to promote hydrolysis of the peptidyl(2A)-tRNA(Gly) ester linkage, thereby releasing the polypeptide from the translational complex, in a manner that allows the synthesis of a discrete downstream translation product to proceed. This process produces a ribosomal 'skip' from one codon to the next without the formation of a peptide bond.


Assuntos
Aphthovirus/metabolismo , Poliproteínas/biossíntese , Biossíntese de Proteínas , Processamento de Proteína Pós-Traducional , Proteínas Virais/biossíntese , Animais , Aphthovirus/genética , Endopeptidases/metabolismo , Glucuronidase/genética , Glucuronidase/metabolismo , Oligopeptídeos/metabolismo , Poliproteínas/genética , Puromicina/metabolismo , RNA Viral/metabolismo , Coelhos , Proteínas Recombinantes de Fusão/biossíntese , Proteínas Recombinantes de Fusão/genética , Ribossomos/metabolismo , Transcrição Gênica , Proteínas Virais/genética
11.
J Gen Virol ; 82(Pt 5): 1027-1041, 2001 May.
Artigo em Inglês | MEDLINE | ID: mdl-11297677

RESUMO

The 2A/2B cleavage of aphtho- and cardiovirus 2A polyproteins is mediated by their 2A proteins 'cleaving' at their own C termini. We have analysed this activity using artificial reporter polyprotein systems comprising green fluorescent protein (GFP) linked via foot-and-mouth disease virus (FMDV) 2A to beta-glucuronidase (GUS) -- forming a single, long, open reading frame. Analysis of the distribution of radiolabel showed a high proportion of the in vitro translation products (approximately 90%) were in the form of the 'cleavage' products GUS and [GFP2A]. Alternative models have been proposed to account for the 'cleavage' activity: proteolysis by a host-cell proteinase, autoproteolysis or a translational effect. To investigate the mechanism of this cleavage event constructs encoding site-directed mutant and naturally occurring '2A-like' sequences were used to program in vitro translation systems and the gel profiles analysed. Analysis of site-directed mutant 2A sequences showed that 'cleavage' occurred in constructs in which all the candidate nucleophilic residues were substituted -- with the exception of aspartate-12. This residue is not, however, conserved amongst all functional '2A-like' sequences. '2A-like' sequences were identified within insect virus polyproteins, the NS34 protein of type C rotaviruses, repeated sequences in Trypanosoma spp. and a eubacterial alpha-glucosiduronasesequence(Thermatoga maritima aguA). All of the 2A-like sequences analysed were active (to various extents), other than the eubacterial alpha-glucosiduronase 2A-like sequence. This method of control of protein biogenesis may well not, therefore, be confined to members of the PICORNAVIRIDAE: Taken together, these data provide additional evidence that neither FMDV 2A nor '2A-like' sequences are autoproteolytic elements.


Assuntos
Aphthovirus/metabolismo , Proteínas Virais/biossíntese , Sequência de Aminoácidos , Animais , Aphthovirus/genética , Sequência de Bases , Cisteína Endopeptidases/genética , Cisteína Endopeptidases/metabolismo , DNA Viral , Glucuronidase/genética , Proteínas de Fluorescência Verde , Vírus de Insetos/genética , Vírus de Insetos/metabolismo , Proteínas Luminescentes/genética , Dados de Sequência Molecular , Mutagênese Sítio-Dirigida , Mutação Puntual , Proteínas Recombinantes de Fusão/biossíntese , Proteínas Recombinantes de Fusão/genética , Rotavirus/genética , Rotavirus/metabolismo , Trypanosoma/genética , Trypanosoma/metabolismo , Proteínas Virais/genética
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